.\" $OpenBSD: CONF_modules_load_file.3,v 1.10 2021/08/03 18:49:30 schwarze Exp $
.\" full merge up to: e9b77246 Jan 20 19:58:49 2017 +0100
.\" selective merge up to: d090fc00 Feb 26 13:11:10 2019 +0800
.\"
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.\" Copyright (c) 2021 Ingo Schwarze <schwarze@openbsd.org>
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.Dd $Mdocdate: August 3 2021 $
.Dt CONF_MODULES_LOAD_FILE 3
.Os
.Sh NAME
.Nm CONF_modules_load_file ,
.Nm CONF_modules_load ,
.Nm X509_get_default_cert_area
.Nd OpenSSL configuration functions
.Sh SYNOPSIS
.In openssl/conf.h
.Ft int
.Fo CONF_modules_load_file
.Fa "const char *filename"
.Fa "const char *appname"
.Fa "unsigned long flags"
.Fc
.Ft int
.Fo CONF_modules_load
.Fa "const CONF *cnf"
.Fa "const char *appname"
.Fa "unsigned long flags"
.Fc
.In openssl/x509.h
.Ft const char *
.Fn X509_get_default_cert_area void
.Sh DESCRIPTION
The function
.Fn CONF_modules_load_file
configures OpenSSL using the file
.Fa filename
in
.Xr openssl.cnf 5
format and the application name
.Fa appname .
If
.Fa filename
is
.Dv NULL ,
the standard OpenSSL configuration file
.Pa /etc/ssl/openssl.cnf
is used.
If
.Fa appname
is
.Dv NULL ,
the standard OpenSSL application name
.Qq openssl_conf
is used.
The behaviour can be customized using
.Fa flags .
.Pp
See the
.Sx EXAMPLES
section for additional functions that may need to be called.
Calling configuration functions in the right order for the intended
effect can be tricky because many configuration functions internally
call each other.
.Pp
.Fn CONF_modules_load
is identical to
.Fn CONF_modules_load_file
except it reads configuration information from
.Fa cnf .
.Pp
The following
.Fa flags
are currently recognized:
.Bl -tag -width Ds
.It Dv CONF_MFLAGS_IGNORE_ERRORS
Ignore errors returned by individual configuration modules.
By default, the first module error is considered fatal and no further
modules are loaded.
.It Dv CONF_MFLAGS_SILENT
Do not add any error information.
By default, all module errors add error information to the error queue.
.It Dv CONF_MFLAGS_NO_DSO
Disable loading of configuration modules from DSOs.
.It Dv CONF_MFLAGS_IGNORE_MISSING_FILE
Let
.Fn CONF_modules_load_file
ignore missing configuration files.
By default, a missing configuration file returns an error.
.It CONF_MFLAGS_DEFAULT_SECTION
If
.Fa appname
is not
.Dv NULL
but does not exist, fall back to the default section
.Qq openssl_conf .
.El
.Pp
By using
.Fn CONF_modules_load_file
with appropriate flags, an application can customise application
configuration to best suit its needs.
In some cases the use of a configuration file is optional and its
absence is not an error: in this case
.Dv CONF_MFLAGS_IGNORE_MISSING_FILE
would be set.
.Pp
Errors during configuration may also be handled differently by
different applications.
For example in some cases an error may simply print out a warning
message and the application may continue.
In other cases an application might consider a configuration file
error fatal and exit immediately.
.Pp
Applications can use the
.Fn CONF_modules_load
function if they wish to load a configuration file themselves and
have finer control over how errors are treated.
.Sh RETURN VALUES
.Fn CONF_modules_load_file
and
.Fn CONF_modules_load
return 1 for success and zero or a negative value for failure.
If module errors are not ignored, the return code will reflect the return
value of the failing module (this will always be zero or negative).
.Pp
.Fn X509_get_default_cert_area
returns a pointer to the constant string
.Qq "/etc/ssl" .
.Sh FILES
.Bl -tag -width /etc/ssl/openssl.cnf -compact
.It Pa /etc/ssl
standard configuration directory
.It Pa /etc/ssl/openssl.cnf
standard configuration file
.El
.Sh EXAMPLES
Load a configuration file and print out any errors and exit (missing
file considered fatal):
.Bd -literal
if (CONF_modules_load_file(NULL, NULL, 0) <= 0) {
	fprintf(stderr, "FATAL: error loading configuration file\en");
	ERR_print_errors_fp(stderr);
	exit(1);
}
.Ed
.Pp
Load default configuration file using the section indicated
by "myapp", tolerate missing files, but exit on other errors:
.Bd -literal
if (CONF_modules_load_file(NULL, "myapp",
    CONF_MFLAGS_IGNORE_MISSING_FILE) <= 0) {
	fprintf(stderr, "FATAL: error loading configuration file\en");
	ERR_print_errors_fp(stderr);
	exit(1);
}
.Ed
.Pp
Load custom configuration file and section instead of the standard one,
only print warnings on error, missing configuration file ignored:
.Bd -literal
OPENSSL_no_config();
ENGINE_load_builtin_engines();
OPENSSL_load_builtin_modules();
if (CONF_modules_load_file("/something/app.cnf", "myapp",
    CONF_MFLAGS_IGNORE_MISSING_FILE) <= 0) {
	fprintf(stderr, "WARNING: error loading configuration file\en");
	ERR_print_errors_fp(stderr);
}
.Ed
.Pp
In the previous example, the call to
.Xr OPENSSL_no_config 3
is required first to suppress automatic loading
of the standard configuration file, and the calls to
.Xr ENGINE_load_builtin_engines 3
and
.Xr OPENSSL_load_builtin_modules 3
are needed so that the configuration of builtin modules and engines
is also loaded in addition to the configuration of
.Qq myapp .
.Pp
Load and parse configuration file manually, custom error handling:
.Bd -literal
FILE	*fp;
CONF	*cnf = NULL;
long	 eline;

fp = fopen("/somepath/app.cnf", "r");
if (fp == NULL) {
	fprintf(stderr, "Error opening configuration file\en");
	/* Other missing configuration file behaviour */
} else {
	cnf = NCONF_new(NULL);
	if (NCONF_load_fp(cnf, fp, &eline) == 0) {
		fprintf(stderr, "Error on line %ld of configuration file\en",
		    eline);
		ERR_print_errors_fp(stderr);
		/* Other malformed configuration file behaviour */
	} else if (CONF_modules_load(cnf, "appname", 0) <= 0) {
		fprintf(stderr, "Error configuring application\en");
		ERR_print_errors_fp(stderr);
		/* Other configuration error behaviour */
	}
	fclose(fp);
	NCONF_free(cnf);
}
.Ed
.Sh SEE ALSO
.Xr CONF_modules_free 3 ,
.Xr ENGINE_load_builtin_engines 3 ,
.Xr ERR 3 ,
.Xr OPENSSL_config 3 ,
.Xr OPENSSL_load_builtin_modules 3
.Sh HISTORY
.Fn X509_get_default_cert_area
first appeared in SSLeay 0.4.1 and has been available since
.Ox 2.4 .
.Pp
.Fn CONF_modules_load_file
and
.Fn CONF_modules_load
first appeared in OpenSSL 0.9.7 and have been available since
.Ox 3.2 .